Majority Leader Reid filed for cloture on the entire farm bill yesterday afternoon. The cloture request will "ripen" early tomorrow. At that point the Senate will vote on whether to end debate on the farm bill.
Even if the cloture vote is successful there will still be a period of voting on amendments after it passes. Germane amendments can also be considered during the period leading up to the cloture vote (i.e. today), and we expect Senator Harkin to attempt to start that debate later today. However that has been tried several times already, only to succumb to objections from the Republican side of the aisle each time. If the cloture vote fails, expect the bill to be set aside for an undetermined amount of time.
You can read some more about the ongoing, and sometimes puzzling situation in this Reuters article.